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Full text of "Text Book Of Mechanical Engineering"

1194                         Appendix  VI.

resisted by the coupling rod f, which is adjustable in length.                    j

These levers, turning freely on their fulcra, are the equivalent
of the Panhard rope, while being more sensitive.

As already indicated, the form of modern car has essentially                    ;

settled down to that of front vertical engine and back-driving
wheels, but two other forms out of the many may be described. The
Duryea Car, Fig. 1054, is typical of American development, the
engines F being horizontal, and the speed, being decreased by                   v"

two sets of epicyclic gear at c, is transmitted by chain to drum E,
in which are two brakes for the two parts of the live axle. The
steering rod A connects to Ackermann levers B as usual. Each
epicyclic box will give two speeds, one when the gear is in action                   j

and one when  running solid, so there are  four speeds and a                   1

reverse provided.    Perhaps the fault of this car lies in the large

11                       portion of the running weight that is carried on the hind wheels.

^                            The Wilson-Pilcher Car, Fig. 1055, is driven from four or six                    \

cylinders with opposed pistons, and any little engine vibration is
further relieved by hanging the engine frame at the front end,
from a high support, steadying by means of springs between the
cylinder heads and the main frame. The fly-wheel L is placed in                    ]>

front, and the shaft clutch is at A, while the two epicyclic boxes
B and c provide for speed reduction. The forward or reverse
motion, as may be required, is effected by moving the wheels D
and E axially as one block, through lever H, so as to gear                     '

respectively with pinion F ; the compensating gear being within                   4

box G, and the brake drum at M.    The change gear is shewn in                     j

Fig. 1056, where an annular spur wheel A is supposed to be fixed
to the frame F, while a second loose wheel L is connected thereto '                 f

through an intermediate pinion c mounted on an arm B.   When B                     I

is rotated through a circle, wheel L partakes of the usual two

motions, and will have revolved i -f  times. If the diameter of A
be twice L, the rotations of L will be three times those of the
arm B. Supposing now L is on the engine shaft, and the pro-
peller shaft is rigid with B. Then the propeller shaft will have
one-third the speed of the engine shaft, and of course other ratios
mil give other speeds. Further, if A be freed and the arm B
made rigid with L, the whole rotates solidly, and the two shafts